"It also allows us to reduce the number of stolen vehicles and has a role to play in reducing death and injury on our roads by identifying unsafe vehicles and drivers without the correct documentation."

ANPR can detect number plates even when vehicles are being driven at more than 100mph - and it can check up to 3,000 plates every hour.

The registration numbers are then checked against records from the DVLA, the Police National Computer and local intelligence computer systems.

Police say vehicles are only stopped "where intelligence suggests that some form of road traffic offence has been committed, or when there is a known police interest in that vehicle".